The present invention generally relates to a door control mechanism including latching members and keeper members for releasably latching and maintaining a pivoted door in a closed position and, more particularly, for effecting alignment of relatively large pivoted doors of truck trailers and/or large cargo containers relative their associated door frames and the like.
Trucks, trailer bodies and large cargo or shipping containers have enclosed bodies which are typically provided with a generally rectangular door frame at one end of the container or the like. A pair of doors usually define one end wall of the container. Typically, the doors are adapted to pivotally swing within the plane of the door frame and are constructed as large as possible to facilitate loading and unloading of the container. Various door control devices are used to latch and maintain the doors in a closed position and to reduce or eliminate transverse distortion, or racking, in the trailer bodies and cargo containers.
To maximize internal cargo space, and since outside measurements of cargo containers are substantially regulated by Industry standards, the container is typically fabricated from relatively thin materials. The container door frame includes an upper transverse header and a lower transverse sill which are welded or otherwise joined by vertical sideframe members.
As the size of truck trailers and cargo containers has increased, a combination of changes have been made in the configurations of trailers and containers, including greater trailer length and larger door openings. Enlargement of the door openings has been achieved by narrowing the associated door frame members housing or framing the doors.
Because of the relatively large size and weakness of the frame members, under certain circumstances, a racking effect is often applied to the container and, thus, the door frame is subject to considerable distortion. Such racking effect causes the header to move transversely and generally parallel relative to the lower sill, thus, tending to distort the door frame members from a generally rectangular configuration into a trapezoidal configuration. Such xe2x80x9crackingxe2x80x9d typically occurs when the cargo container is not standing level, i.e., the rear wheels of the vehicle are on different levels. Such racking action also tends to occur from twisting or jostling of the container during travel, particularly at high speeds.
It is common practice to utilize the doors, when closed, to add stiffness to the frame of the cargo container. A common and well known device for holding the doors in their closed position is disclosed in U.S. Pat. No. 4,869,023 to R. J. Bakula, et al. and includes a rotary bar locking mechanism associated with each door on the cargo container. Such a locking mechanism includes an elongated lock rod extending generally the height of the door and having a latching member at each end thereof arranged for engagement with a keeper member on the door frame.
Besides having to narrow the frame members, a related problem with the ever increasing need to enlarge the size of the trailers and doors is the reduction in surface area on the frame members available for attachment of the keeper members. This, in turn, has diminished the vertical height or width available for the design of cams on the latching members and keeper members and has thereby limited the amount of door misalignment that is correctable by the cam designs on the latching members and keeper members.
At least at one end, the door latching member disclosed in the ""023 device includes an elongated wedge shaped locking tongue. That is, the distal end of the locking tongue on one door latching member extends a further radial distance from the axis of rotation of the lock rod than does the distal end of the locking tongue on other door latching member. Accordingly, the longer locking tongue engages its respective keeper and, thus, draws or aligns the respective door until the locking tongue on the other door latching member engages with its respective keeper.
During actual use or practice, however, it has been discovered the racking of the cargo container can be such that the distal end of the longer locking tongue is such that it abuts with its respective keeper. Alternatively, the longer locking tongue engages with its respective keeper but, because of its relative narrow width, has limited gathering capability. Thus, in some instances, the latching member having the longer tongue tends to inhibit and cause problems with the other latching member engaging with its respective keeper thereby adding difficulty in closing he doors of the cargo container. Moreover, the cam design on some latching members are such that they facilitate alignment of the respective door only in a single direction. Thus, when the cargo container is racked in a particular direction, the cam design can offer only minimum or little assistance in correcting door misalignment problems relative to the door frame.
Thus, there is a continuing need and desire for a door control mechanism having a latching member designed to facilitate alignment of a cargo container door and which is configured to facilitate its introduction into locking engagement with the respective keeper member of the control mechanism.
In view of the above, and in accordance with a first aspect of the present invention, there is provided an improved latching member for a door control mechanism adapted for use with a pivotal door on a cargo container. The latching member includes a single tine or locking tongue preferably formed integral with and extending from a head portion of the latching member. In a preferred form, the latching member tine or tongue has converging curved surfaces extending from the head portion toward a distal end of the locking tine.
A salient feature of the present invention relates to designing the distal end of the locking tongue or tine with a taper whereby promoting introduction of the tine into latching relation relative to a keeper member. In one form, the tapered configuration involves a slanting surface extending at an acute angle ranging between about 25xc2x0 and about 60xc2x0 for a distance measuring between about 0.093 inches and about 0.500 inches from an apex of the tine toward the head portion. In another form, the tapering configuration is provided at the distal end of the tine by providing two generally planar slanted and converging surfaces angling toward the apex of the tine. In this form, each slanted surface is disposed at a generally equal angle relative to a generally horizontal plane while each slanted surface extends inwardly toward the head portion of the latching member for a distance of about 0.200 inches.
Another salient feature relates to configuring the latching member tine with diverging slanted surfaces extending from the upper and lower surfaces of the locking tongue or tine and extending toward said head portion. Configuring the locking tongue with diverging slanted surfaces in the area where the tongue and head portion are conjoined increases its cross sectional area, thus, adding strength and rigidity to the elongated tine or locking tongue.
Another aspect of the present invention relates to a door control mechanism which facilitates alignment of a cargo container door relative to the door frame and latching thereof in a closed position. The door to be aligned and latched is typically hinged to a frame including a transverse header and sill which are joined by vertical side frame members.
According to this aspect of the invention, the door control mechanism includes a rotatable operating shaft adapted to be mounted parallel to an outer face of the cargo door about a substantially fixed vertical axis spaced from a hinged edge of the door. First and second latching members are arranged at opposite ends of the shaft to turn in timed unison therewith. Each latching member includes a locking tongue extending in a first lateral direction from a head portion of the latching member. When secured to opposed ends of the shaft, it is common to configure the latching members such that one latching member has significantly greater gather than the other latching member.
First and second keeper members, adapted for securement to the header and sill of the door frame, are configured to cooperate with the latching members in a manner promoting alignment and positioning of the door as a function of operation of the mechanism. Each keeper member has a base with a tapered surface leading toward a latch locking zone of the keeper member. The keeper member adapted to be secured to the sill is preferably configured such that the tapered surface thereon is specifically designed to cooperate with that latching member having the greater gather whereby facilitating alignment of the door relative to the door frame.
According to this aspect of the invention, both latching members are configured and secured to the shaft such that the distal end of the tine on each locking member is introduced into the latch locking zone of the respective keeper members substantially simultaneously thereby offering an improved gathering range when the door control mechanism is operated to position the latching members in locking relation relative to their respective keeper members. In one form, the latching member having greater gathering capability is preferably disposed to cooperate with that keeper member adapted to be secured to the sill of the door frame. In a most preferred form, the latching member arranged toward an upper end of the operating shaft is configured in accordance with the first aspect of this invention mentioned and described above.
A primary object of this invention is to provide a door control mechanism latching member having a locking tongue or tine which is configured to imparting aligning movements to a misaligned cargo container door but yet which is configured to facilitate introduction of a distal end of the tine into operable association with an associated keeper member.
Another object of this invention is to provide new and novel design changes to an elongated tongue or tine of a door latching member whereby facilitating its operation in combination with a respective keeper while maintaining sufficient strength and rigidity for the latching member to promote alignment of misaligned cargo container doors.
Still another object of this invention is to provide a door control mechanism having an operating shaft with latching member at opposed ends thereof and which are adapted to combine with keeper members arranged on the door frame, with the locking tongues or tines on the latching members being configured and secured to the operating shaft such that the distal end of the tine on each locking member is introduced into a latch locking zone of the respective keeper members substantially simultaneously thereby offering an improved gathering range when said mechanism is operated to position said latching members in locking relation relative to their respective keeper members.
These and other objects, aims, and advantages of this invention will become more readily apparent from the following detailed description, the drawings, and the appended claims.